Technology

The MarTECH^® loop slurry process was formally introduced in 1961. The process is creating unimodal products in a single loop reactor (Fig. 1)^[1]. 

Figure 1 - Single Loop reactor of the MarTECH^® SL process for creating unimodal products^[1].

Slurry polymerization takes place in the presence of an inert solvent at a temperature below 135°C. The polymer formed in the presence of a catalyst is in the solid state. The liquid-phase process takes place at a temperature between 85-110°C in a loop reactor. The catalyst and the inert solvent are introduced into the loop reactor where ethylene and an α-olefin are circulating. The inert solvent is used to dissipate heat as the reaction is highly exothermic. A cooling jacket is also used to dissipate heat. The concentration of polymer products in the slurry is 25% by weight. The polymer is concentrated in settling legs to about 60% by weight slurry and continuously removed. The solvent is recovered by hot flashing. The polymer is dried and pelletized. The conversion of ethylene to polyethylene is very high (95%-98%)^[2].

Chevron Phillips Chemical claims that the MarTECH^® loop slurry process have demonstrated on-stream factors of 98% and higher on an annual basis^[1]. 

Two SL plants are scheduled for startup in late 2026 at Ras Laffan in Qatar with a capacity of 850,000 tonnes per year each^[3]. Two SL plants are also scheduled to go into operation in 2028 at the Golden Triangle project on the U.S. Gulf Coast with a capacity of 1,000,000 tonnes per year each^[4].  

By Oct 2024, more than 80 plants have been licensed in 20 countries^[1].

References

1. Chevron Phillips CHEMICAL, What We Do, Licensing, Polyethylene Technology (accessed 4^th Oct 2024).
2. Kevin, University at Buffalo, Courses, CE435, High Density Polyethylene.
3. Chevron Phillips CHEMICAL, RAS LAFFAN PETROCHEMICAL PROJECT (accessed 4^th Oct 2024). 
4. 2b1st Consulting, 23rd Mar 2023, Chevron Phillips Golden Triangle Polymers Gulf Coast II.